Black Magic is mostly based around the elements. Also most of the time it based on levels, such as Fire3 being stronger then Fire2. Here is a list of Black Magic spells.
Fire-Burn your enemies with a blast of fire.
Ice-Smash your enemies with shards of ice.
Bolt-Toast your enemies to a crisp with lightning.
Quake-Rumble the group beneth your foes to cause damage, make sure they aren't flying.
Water-A weaker attack that hits enemies with bubbles or waves of water.
Flare-The Ultimate fire attack.
Ultima-THE ULTIMA magic attack, usually green energy.